I was checking the belt deflection on the Magnum today and noticed I have 1&7/16 inches of deflection when I should be at 1&1/8 inches. My question is, do you add or remove shims inbetween the sheeves to increase tension? And how much does one shim change your tension?
Yes the belt is the right length @40 inches and also the right width.

 

Removing shims will tighten the belt. I have no idea how much removing one shim will tighten the belt. Hope this helps